Ignition coils are known for use in connection with an internal combustion engine such as an automobile engine. Ignition coils typically include a primary winding, a secondary winding, and a magnetic circuit. The magnetic circuit conventionally may include a central core extending along an axis and located radially inward of the primary and secondary windings and magnetically coupled thereto. In one arrangement, a C-shaped high permeance structure is included to provide a high permeance magnetic return path. The high permeance structure may include a base section from which a pair of legs extends. The central core is placed between the legs such that the axis of the core extends through the legs of the high permeance structure and such that at least one end of the core is spaced apart from the leg to which it is adjacent to define an air gap. The primary winding, secondary winding, core and high permeance structure are contained in a case formed of an electrical insulating material. The case is filled with an insulating resin or the like for insulating purposes. In this configuration, insulating resin that fills the air gap may be subject to stress from the core during operation of the ignition coil. This stress may lead to undesired performance of the ignition coil.
What is needed is an ignition coil which minimizes or eliminates one or more of the shortcomings as set forth above.